Note 4 - Long-term Debt - Aggregate Minimum Principal Maturities on Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
2021	$ 0
2022	0
2023	0
2024	595
2025	0
Thereafter	3,440
Total Debt	4,035	$ 3,760
The 2019 Senior Credit Facility [Member]
2021	0
2022	0
2023	0
2024	595
2025	0
Thereafter	1,190
Total Debt	1,785
2026 Notes [Member]
2021	0
2022	0
2023	0
2024	0
2025	0
Thereafter	700
Total Debt	700	700
2027 Notes [Member]
2021	0
2022	0
2023	0
2024	0
2025	0
Thereafter	750
Total Debt	750	750
2030 Notes [Member]
2021	0
2022	0
2023	0
2024	0
2025	0
Thereafter	800
Total Debt	$ 800	$ 0

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(a))
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-Section 50
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